1. Field of the Invention
The present invention relates to an electronic assembly that contains a two-phase material to absorb heat generated within the assembly.
2. Background Information
Integrated circuits are typically assembled into packages that are mounted to a printed circuit board. The integrated circuits generate heat which must be removed from the packages to insure that the junction temperatures do not exceed a specified level. Some electronic assemblies incorporate heat slugs and heat sinks to facilitate the transfer of heat away from the package. The heat may be transferred from the heat sink by a flow of air that is generated by a fan.
For high powered integrated circuits such as microprocessors there have been developed electronic assemblies that incorporate heat pipes to transfer heat away from the packages. A heat pipe contains a fluid that is enclosed by an outer metal tube. Heat is transferred into the tube and evaporates the fluid at an evaporator end of the heat pipe. The evaporated fluid then flows to a condenser end of the pipe where the heat is removed and the fluid returns to a liquid phase. The liquid flows back to the evaporator end through a wick that is attached to the inner surface of the outer tube.
Integrated circuits may undergo a "power burst" wherein the circuit generates an above average amount of heat. The power burst may increase the temperature of the heat sink, the package and the integrated circuit.
There have been developed systems that sense the initiation of a power burst and increase the fan speed to improve the heat transfer rate from the heat sink and package. Unfortunately, there is a time delay between the initiation of the power burst and the effective removal of additional heat from the package. Additionally, the higher fan speed may increase the noise of the system. It would be desirable to provide an electronic assembly that can dissipate a power burst from an integrated circuit without significantly increasing the temperature of the circuit.